=== Warning: Sad Story ===
Beware, this is not going to be an enjoyable story. Thought of writing this story as something of a lore reinterpretation after the reworks for Kayle and for Morgana were released. It's intended to be an explanation about how the two initially became angels before their conflict in the angel realm that led to Kayle's justification fixation and Morgana's return to the mortal plane, leading to when they became recruited to the Institute of War. Personally I am a Morgana main as a player and writing fan fiction about computer games has been a hobby of mine for over 2 decades.
Kayle and Morgana were twin sisters, in their early years of elementary school. Kayle had blonde hair, and Morgana had very dark purple hair. Morgana, going by the name Morg or Morgy for short, had a bit darker purple skin color, while Kayle had a bit brighter golden skin color. In their early years as kids, Morg and Kayle lived as twin sisters, innocent kids, playing and living with their two parents, father and mother.
Unfortunately, before either of them could graduate from elementary school, their homeland in Runeterra was struck by an invasion, which would be remembered as the Rune Wars. As an unknown force of magic invaded their world, their village seemed to surely be on a path toward decimation and disintegration. Morg and Kayle's mother left their family to become a warrior, fighting in battle to defend their village, but in failure, their mother was killed in battle.
After their mother had died, their father took Kayle and Morgana to leave their village, and move to a safer area, taking residence in what is now known as Demacia. However, the family's notion of safety proved to be temporary, as Demacia was also in the path of the Rune War's destruction. They had only lived in Demacia for a few years when their new home was struck by bombings from the sky.
The family had been at rest, but they soon became aware of the bombings, that had followed them from their old village which was now completely obliviated, to their newly adapted homeland of Demacia. They heard the sounds from miles away, 100 km away they could hear acreages of neighborhoods, just exploding as the invaders dropped explosive bombs from their flightcrafts in the sky, targeting nearby houses and buildings, destroying the homes and killing their occupants. Morgana and Kayle played helplessly in their neighborhood, aware that the bombings were approaching, but without an escape plan, and still recovering from their move to Demacia, they had to just ignore the impending invasion.
Their father sat inside, watching the children playing outside, but when he noticed the helicopters and airplanes taking course for his neighborhood, and saw a space station turn to reorient its satellite broadcast toward the flying fleet of bombers' destination, he called the kids inside. He thought that he'd made the best possible move to leave their old village after their mother's death, before their village was eradicated entirely. But he saw that moving to Demacia was only buying time, he knew now that the enemies were not leaving any of Runeterra intact, he'd heard of the nearby neighborhoods being bombed for months prior to today, and he was fully aware that this evening would be their neighborhood's last day as the enemy troops were advancing in the sky and would surely fly above their street before sunset, probably to bomb their house and their neighbors' houses during the night.
So when he called Kayle and Morgana inside, some of their new friends, who were still not even 10 years old yet, came inside with them, drinking water and juice, having some snacks which they shared politely. The other kids sat down and relaxed, but as the afternoon gave way to evening and the sun was settings, they said their friendly goodbyes, smiling, hugging, waving goodbye before they returned home to their parents' homes. So it was just Kayle and Morgana and their father left at home, about that time when they could have some dinner, do their homework, and prepare for tomorrow's schoolwork before going to sleep.
Sadly their father had been a bit distracted to prepare dinner. He had plenty of leftovers from their dinner earlier in the week though, so they all heated up some food, and sat down at the table. Somewhat surprisingly, they heard the sounds of helicopters and airplanes directly above their house, as they were eating, and by the time they finished eating, the sun had fallen, casting them in the dark of night.
As they finished eating, their father told Morgana and Kayle, "Don't forget to brush your teeth before you go to sleep, and have some water."
Kayle and Morg laughed at each other, quite familiar with their nightly routine, but too bored to fuss over it. They looked at each other and could tell there were much more interesting things that they'd rather discuss after their early dinner.
"When we were outside playing catch with Tiinaa and Margaret, none of us dropped the ball once. Not once. We used Tiinaa's rubber ball. The blue one. Tiinaa let Margaret borrow it when we went home," Kayle informed their father, as Morgana's implicative nod and straight face confirmed her agreement with the truth of her sister's story.
Their father said "Okay, that's quite good."
Morgana continued the story. "Kayle got a lot better at throwing, and I got a lot better at catching. Her passes actually landed in their arms for once. And I had to jump to catch some passes, but I got all of them."
As the sounds of the airplanes and helicopters grew more distant, their father said "Alright. I wonder how high you had to jump."
Kayle looked upward, making an estimation in comparison to the height of the ceiling. "About as high as the ceiling," she said, "but maybe a little lower."
The three of them laughed at the absurd lack of precision in Kayle's estimation.
"Well, I'm going to go outside and take a short walk," their father said. "Do you think you'll be okay for five or ten minutes? I just have to stretch my legs."
The kids were fine with that, saying sure, they'd be happy to wait around the house by themselves. So he went outside, walking down the road, and gazing at the sky.
Meanwhile Kayle and Morgy sat and relaxed, full from their dinner, and chilling.
Their father took a 5-minute walk, and as he approached the house, he could see the airplanes above, returning toward their neighborhood. He went inside, and found the kids vegetating, just tired from a day of school, an afternoon of play, and a nice dinner. He decided it was once again time to address the situation.
"Alright, Morgana, Kayle, it looks like the airplanes are coming to our neighborhood tonight. We all heard them earlier, did we not?" he said.
Kayle knew she'd heard them too.
So did Morgana. "Yeah, we heard them," said Morg.
Kayle corroborated that statement, "I also heard them flying above us."
Morgana asked, "So what does that mean? They're gonna explode our house and Margaret and Tiinaa's houses tonight?"
Their father looked frustrated and disappointed. "Yes, I assume so," he said sternly. "It's too bad, but we already moved once a few years ago. There's nowhere safe for us to move to. These magical creatures are attacking our world and they are totally committed to destroying all of humanity."
Having heard her father's remarks, Kayle looked confused and upset. "So what should we do now?" She glanced at her sister, Morgana, who was fighting back tears after remembering her mother.
Morgana took a moment to rally up her resolve. "We have a few options now." The sounds of the airplanes grew louder, meaning they were getting close. "We could try to avoid the bombs, since they will surely aim to drop them on the buildings around here. We could try to knock the planes down, or make them fly away. Or we could just accept defeat and die in the bombings and be with mommy in the afterlife." The mention of their mother reminded Kayle of her haunted past, and Kayle sobbed in tears of despair, as the two sat next to each other. Thier father looked to be struck with grief. Kayle remained speechless, crying next to the angered Morgana.
Their father gave them one last glance, an attempt to comfort them. The airplanes had quieted their advance, but they were just above their neighborhood, and began to drop their bombs, targeting the houses and other buildings. Kayle watched in tears as their neighbors' homes were impacted and quickly burned down. She grabbed Morgana's hand, and their father sat down with them for a moment, and their house was struck next. As the explosive bombs landed on their house, they felt the impact of the bombs hitting their roof, falling through to the ground at their feet, and exploding in their face into a chemical fire that overtook the entire house instantly. Seconds after their conversation ended in tears, the three of them were crushed by the fallen ceiling and burned to death, along with the rest of their friends in the neighborhood. The airplanes continued to the end of the neighborhood, before turning away in retreat. Afterward, some helicopters ventured to the site of the bombing, to check that their attack had killed everyone who lived there, and having verified that there were no signs of any humans still alive, the helicopters left as well.
Kayle, Morgana, and their father, having been killed, continued to exist merely as subatomic particles, their bodies having being rapidly disintegrated earlier. By the morning, their neighborhood only remained in the form of tiny fragments of buildings and the ground they'd stood on the night before, with no traces of remaining life. The innocent children, the friends of Morg and Kayle, the parents and adults of the community, and everyone who'd once lived there were relegated to become a warning sign, for the other neighborhoods nearby, who would surely soon be next to be destroyed by the Rune Wars. In the afterlife, the mother of Morg and Kayle, who had waited very few years and months for her family to join her, welcomed her kids and their dad, into her realm.